Regarding the Jewish religious leaders of that time, he said:
“You have made the word of God invalid because of your tradition.
YOU HYPOCRITES, Isaiah aptly prophesied about you when he said:
‘This people honor me with their lips,
but their hearts are far removed from me.
It is in vain that they keep worshipping me,
for they TEACH COMMANDS OF MEN as DOCTRINES.’” (Matthew 15:6-9; compare with Isaiah 29:13.)
Christ also strongly warned his true followers to NOT get involved with the many false followers he would come to have:
"On judgment day many will say to me, ‘Lord! Lord! We prophesied ...
cast out demons ... & performed many miracles in your name.’
"But I will reply, ‘I NEVER KNEW YOU. GET AWAY FROM ME
you who BREAK GOD'S LAWS.’" (Matthew 7:22-23, NLT)
"For FALSE messiahs and FALSE prophets will rise up and perform signs and wonders so as to DECEIVE, if possible, the chosen ones.
You, then, WATCH OUT. . . ." (Mark 13:22-23, NLT)
This makes it clear that true Christians will have no part with those who teach false things about God & God's Word. For Christ describes his followers in this way:
"Nevertheless ... the TRUE worshippers will worship the Father with spirit and TRUTH, for indeed, the Father is looking for ones like these to worship him. God is a Spirit, and those worshipping him MUST worship with spirit and TRUTH." (John 4:23-24, NWT)
For this reason, the basis for deciding what truth is should be what God says,rather than what man-made religions teach, since . . .
"All Scripture is inspired of God and beneficial for teaching, for reproving, for setting things straight, for disciplining in righteousness." (2 TImothy 3:16, NWT)
"For prophecy was at no time brought by man’s will, but men spoke from God as they were moved by holy spirit. (2 Peter 1:21, NWT)
"MAKE SURE of all things; hold fast to what is fine."
(1 Thessalonians 5:21, NWT)
"What Can the Bible Teach Us?"
- What Is God's Purpose for Us?
- Who Is God?
- The Bible---A Book from God
- What is God's Purpose for Humankind?
https://www.jw.org/en/publications/books/bible-study/